1. Field of the Invention
This invention relates to a system which may be used to remove from a solution certain substances and, in particular, it relates to removal of chemicals and compounds which are hazardous to the environment or to reclaim substances which are useful for some other purpose.
2. Description of the Prior Art
Environmental protection is of the utmost importance in today's society. Legislators have recognized the threats to the environment and have enacted protective legislation. Compliance with those increasingly stringent environmental protection regulations, however, is one of the greatest challenges facing industry today. Such compliance can become extremely costly to the point where competitive pricing can be jeopardized.
Many methods have been suggested to purify or at least make environmentally acceptable, industrial waste products. In the chemical industry, a particular problem relates to discharge of effluent into water supplies. The effluent must not contain certain substances beyond specific limits even though the water will later be treated in a treatment facility.
For example, certain legislation is directed toward retaining and preserving the biological oxygen demands in water supplies as well as the chemical oxygen demands in water supplies. It is required to minimize certain chemicals, such as ammonia, which are harmful to those qualities.
A variety of devices and methods have been known for purifying waste solutions. For example, it has been known to utilize reverse osmosis, ozonization, and resin ionic exchange.
In addition, it has been known to filter iron precipitates from photochemical solutions prior to discharge. A system for such a procedure is disclosed in U.S. Pat. No. 4,608,177, but it does not provide for removal of ammonia and similar substances.
Unfortunately, such prior art devices can be extremely complex and expensive. There remains a need for a simple, low cost device which can be readily employed to filter undesirable chemicals out of solutions on a smaller scale than the situations that previously known techniques have addressed.
It may also be desirable in other applications to filter out and reclaim useful substances which would otherwise be discarded and wasted. My U.S. Pat. No. 4,662,613 describes a reusable precious metal recovery cartridge which may be used, for example, to recover silver from certain photographic solutions. My U.S. Pat. No. 4,325,732 also discloses a precious metal recovery cartridge.
My prior patents, however, do not focus on removal of hazardous or environmentally unacceptable chemicals from the solution. There remains a need for an effective system which can remove unwanted substances from a solution and which can also be used to recover metals, and which devices may be used in connection with precious metal recovery cartridges, preferably, after the cartridges have been employed to recover the precious metals. As stated hereinbefore, there also remains a need for a simple, low cost device which is disposable and easy to use.